The Electric Car
in [Design]
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From: Robert Latest on 7 Aug 2007 03:34 Rich Grise wrote: > I won "designated driver" one time, and drove this guy's Mercedes 300D. > > What a pig! Had horrendous blind spots, and went 0-60 in about 10 minutes. ;-) Oh, the 300D Great car. I once drove a 200D. Built like a tank, no acceleration at all, but you could probably plough with it. robert
From: MooseFET on 7 Aug 2007 09:47 On Aug 6, 8:48 pm, JosephKK <joseph_barr...(a)sbcglobal.net> wrote: > Mark makol...(a)yahoo.com posted to sci.electronics.design: > > > > > > >> It seems to just argued against using any electric motors at all. > > > Yep, I think the small batteries and electric motor in the Prius > > are there for only 2 reasons.. > > > 1) efficency gained by regenerative braking > > 2) improve the acceleration so the ICE can be smaller also > > improving the efficency. > > > If you had the small ICE without the acceleration boost provided > > by > > the electrics, the acceleration would be poor and people would > > not like the "drivablility". > > > Intersting to note that a flywheel could provide the same > > advantage. > > > In fact I tend to think of the battery and electric motor in the > > Prius is just an electric implementation of a flywheel. > > > Mark > > > Mark > > Yes, and flywheels bring their own issues with changes yaw, pitch > and roll. There will have to be space for the flywheel to spin not > only during normal driving but the vehicle must not become a hazard > if it rolls over in any direction or spins out. I think compressed air is a better way to go.
From: Don Lancaster on 7 Aug 2007 10:42 MooseFET wrote: > > > > I think compressed air is a better way to go. > Go for what? The energy density of compressed air is ludicrously low. Typically one sixth of lead acid or worse. 15 wh/l is hard to acheive. The efficiencies of most compressed air motors are much worse than an ICE. Typically 29 percent or less. No means of efficiently compressing air is known. Efficient compression requires isothermal operation, which can only be approximated by elaborate and costly multi-staging. The fire service proved all this a century ago after throwing bunches of engineering at the proglem. The ONLY thing compressed air has going for it is shop floor convenience. Hydraulics immediately get substituted when serious tail twisting or anything remotely approaching efficiency is needed. See http://www.tinaja.com/glib/energfun.pdf -- Many thanks, Don Lancaster voice phone: (928)428-4073 Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552 rss: http://www.tinaja.com/whtnu.xml email: don(a)tinaja.com Please visit my GURU's LAIR web site at http://www.tinaja.com
From: Eeyore on 7 Aug 2007 11:22 MooseFET wrote: > JosephKK <joseph_barr...(a)sbcglobal.net> wrote: > > Mark makol...(a)yahoo.com posted to sci.electronics.design: > > > > >> It seems to just argued against using any electric motors at all. > > > > > Yep, I think the small batteries and electric motor in the Prius > > > are there for only 2 reasons.. > > > > > 1) efficency gained by regenerative braking > > > 2) improve the acceleration so the ICE can be smaller also > > > improving the efficency. > > > > > If you had the small ICE without the acceleration boost provided > > > by > > > the electrics, the acceleration would be poor and people would > > > not like the "drivablility". > > > > > Intersting to note that a flywheel could provide the same > > > advantage. > > > > > In fact I tend to think of the battery and electric motor in the > > > Prius is just an electric implementation of a flywheel. > > > > Yes, and flywheels bring their own issues with changes yaw, pitch > > and roll. There will have to be space for the flywheel to spin not > > only during normal driving but the vehicle must not become a hazard > > if it rolls over in any direction or spins out. > > I think compressed air is a better way to go. Compressed air power storage is horribly lossy. Graham
From: Guy Macon on 7 Aug 2007 12:59
Don Lancaster wrote: > >MooseFET wrote: >> >> I think compressed air is a better way to go. > >Go for what? > >The energy density of compressed air is ludicrously low. >Typically one sixth of lead acid or worse. 15 wh/l is hard to acheive. > >The efficiencies of most compressed air motors are much worse than an >ICE. Typically 29 percent or less. > >No means of efficiently compressing air is known. >Efficient compression requires isothermal operation, which can only be >approximated by elaborate and costly multi-staging. > >The fire service proved all this a century ago after throwing bunches of >engineering at the proglem. > >The ONLY thing compressed air has going for it is shop floor >convenience. Hydraulics immediately get substituted when serious tail >twisting or anything remotely approaching efficiency is needed. The ONLY thing? There are other advantages. With pneumatics the light-load cycle rate is higher, the piping for distribution doesn't need to have a return path, and in some clean-room applications the system can tolerate traces of ultrapure gas leaking into the working area, but not any sort of liquid. Hydraulics win for strength, efficiency, positional control, stiffness, and safety if a pipe or cylinder bursts. You will never see pneumatics in a bulldozer, and you will never see hydraulics in a machine that puts CDs into CD cases. Having worked as a design engineer for both Parker Hydraulics and SMC Pnuematics, I don't see either of them cutting into the other's business. -- Guy Macon <http://www.guymacon.com/> |